@Muamp Nice headphones yet again. I'm envious of your Pink Floyd experience.
I'm becoming proficient with librecad, so I should be able to make a pair of headphones soon. My time recently has been consumed with an OTL amp build; basically a crack with a different input tube and a different operating point for the output one. It sounds good, but is buzzing.
I have yet to make a diaphragm tensioner or an amp. I'll make an energizer (trafo box) for now, then a direct drive amp. I have been working on a design and consulting Kevin Gilmore. That design should be finished soon.
For tensioners, where did you get your tire from?